1. Field of the Invention
The present invention relates to a flexible printed circuit board assembly, and more particularly, to a flexible printed circuit board assembly, which has a complicated circuit pattern and a connector but can be easily mounted even in a relatively narrow space.
2. Description of the Related Art
Since a flexible printed circuit board assembly has flexibility by which the flexible printed circuit board assembly can be bent by itself, the flexible printed circuit board assembly has been used in various kinds of electrical appliances. For example, a flexible printed circuit board can be installed between a main body and an openable display unit of a notebook computer to transmit an electrical signal between the main body and the display unit, or can be installed between a main body and a movable pickup assembly of an optical disc drive in a computer to transmit a signal therebetween.
Further, the flexible printed circuit board is used in a portable terminal such as a cellular phone or a personal digital assistant (PDA) that a user utilizes to perform communication or to store information while conveniently carrying it with him/her. The cellular phone or PDA comprises a min body containing a signal transmitting/receiving means and a signal processing means; and a display unit that can be opened or closed with respect to the main body. In general, the display unit is slid or folded with respect to the main body so that the display unit can be opened or closed. In such a cellular phone or PDA, since the display unit is opened or closed with respect to the main body, transmission/reception of a signal between the main body and the display unit is performed through the flexible printed circuit board.
Generally, a number of circuit patterns corresponding to a variety of functions of the portable terminal are formed on the flexible printed circuit board. A connector is mounted on the flexible printed circuit board, so that the flexible printed circuit board can be electrically connected through the connector to a main printed circuit board (PCB) of the main body or a PCB contained in the display unit.
There is a recent tendency for a portable terminal to have a variety of additional functions such as the functions of a camera and an MP3 player in addition to a basic communication function. Such diversification of functions inevitably results in complication of printed patterns of a flexible printed circuit board to support transmission and reception of signals corresponding the various functions. The complication of the printed patterns of the flexible printed circuit board means that the area of the flexible printed circuit board becomes larger and the connector inevitably has a large size corresponding thereto.
Referring to FIGS. 1 and 2, the conventional flexible printed circuit board assembly comprises a flexible printed circuit board 1 provided with a plurality of circuit patterns 3 printed thereon at certain intervals, and a connector 2 provided at one side of the flexible printed circuit board 1.
As described above, as the functions of the portable terminal become complicated, various circuit patterns printed on the flexible printed circuit board become more complicated and the number thereof is increased, leading to increase in the required area of the flexible printed circuit board 1 and increase in the size of the connector 2. Further, a plurality of terminals 4 to be electrically connected to the circuit patterns 3 are provided on a bottom surface of the connector 2.
The connector 2 is provided at a location spaced apart by a certain distance L from an end of the flexible printed circuit board 1 and can be connected, for example, to a connector of a portable terminal so as to transmit an electrical signal. The mounting of the connector 2 at the location spaced apart by the distance L from the end of the flexible printed circuit board 1 is because it is necessary to secure an area on which circuit patterns to be connected to terminals 4 placed at an end portion of the connector 2 will be formed. That is, as denoted by reference numeral “A” in FIG. 1, a predetermined area should be provided between the connector 2 and the flexible printed circuit board 1 so as to form the circuit patterns to be connected to the terminals 4 provided at the end portion of the connector.
A stiffener 5 is attached to a bottom surface of the flexible printed circuit board 1, which is a surface opposite to the surface on which the connector 2 is provided. The stiffener 5 is provided to prevent the flexible printed circuit board 1 from being deformed under an atmosphere at a high temperature in the process of connecting the patterns of the flexible printed circuit board 1 to the terminals 4 of the connector 2. The stiffener is made of a synthetic resin material or a metallic material and then attached to the bottom surface of the flexible printed circuit board 1. Moreover, the stiffener 5 is provided to protect and stably support the flexible printed circuit board when the connector of a main body of the portable terminal is connected to or detached from the connector 2. To stably support the flexible printed circuit board 1 as described above, the conventional stiffener 5 is designed to have a width W that is twice as large as the distance from the end of the flexible printed circuit board 1 to the connector 2, as shown in FIG. 2.
However, there is a recent tendency for a personal terminal such as a cellular phone or a PDA to be smaller and slimmer. With the tendency of diversification of functions due to addition of the functions of an MP3 player, a camera including a moving picture, and the like, the number of circuit patterns for transmitting signals increases accordingly. For example, since a PDA has relatively more functions than a cellular phone, the PDA has one hundred or more circuit patterns for transmitting signals, and a connector having one hundred or more terminals or pins corresponding to the circuit patterns.
With the increase in the number of circuit patterns and the size of a connector due to diversification of the functions of a portable terminal, there is limitation on reduction of the size and thickness of the portable terminal. That is, when the circuit patterns to be connected to the connector 2 are designed and arranged in the conventional structure of the portable terminal, there is limitation in that an area including portion “A” around the connector inevitably becomes larger. For example, due to increase in the number of circuit patterns, the size of the connector 2 as well as the distance L between the connector 2 and the end of the flexible printed circuit board are increased inevitably. Accordingly, the entire size of the flexible printed circuit board assembly becomes larger, and thus, there is limitation on miniaturization and slimness of the portable terminal.